OBJECTIVE: 1) To expand our understanding of fetal nutrition and metabolism, particularly in the areas of carbohydrate and amino acid turnover under various biological states such as maternal fasting. 2) To determine rates of protein synthesis and turnover during fetal and neonatal life. 3) To compare rates of glucose and amino acid utilization in pregnant animals of different species. 4) To evaluate the changes in placental blood flow which occur within a litter and during gestation. 5) To study the impact of maternal fasting and hyperinsulinemia upon placental metabolism in vivo. 6) To study the role of estrogens and of estrogen receptors in regulating uterine flow. 7) To evaluate the role of HCG and antitrypsin in immunosuppression. 8) To study the pharmacokinetics of a variety of drugs including furosemide and aminoglycosides in high risk infants. 9) To study the diagnostic potential of serial ultrasound measurements versus CAT scans in the diagnosis of intracranial hemorrhage; and to compare neurologic findings and serial coagulation studies with the onset of intracranial hemorrhage in pre-term babies. 10) To study the induction or non-induction of placentas to cytochrome P-450 dependent metabolic pathways and relate this to exposure to potential environmental inducers.